Fall 2007 Update: Spring Chlorophyll Distribution

The distribution of chlorophyll concentration during the first half of 2007 is shown as a progression of monthly maps with a parallel set of monthly anomaly maps. Chlorophyll anomalies are the ratio of the monthly mean to the long-term mean for the given month (1997-2007). There is a general onshore to offshore gradient where chlorophyll concentrations are greatest in the continental shelf waters, intermediate over the deeper slope water, and lowest in the vicinity of the Gulf Stream and Sargasso Sea. High levels of chlorophyll during the spring occur in the Mid-Atlantic Bight estuaries and enriched coastal waters, and in the tidally mixed central subregions of Nantucket Shoals and Georges Bank. The spring bloom first appears along the coastal regions and in the subregion of Nantucket Shoals during March, but never extends offshore into the Gulf of Maine as indicated by the below average conditions present in April. The bloom, however, persists on Georges Bank through June.